From ca2446e4fde4939da3e58dfd24ede944901fb6e2 Mon Sep 17 00:00:00 2001
From: Martin Holters <martin.holters@hsu-hh.de>
Date: Thu, 14 Sep 2017 14:05:47 +0200
Subject: [PATCH] Make CartesianIndex iterable

Make iterating a CartesianIndex equivalent to iterating the tuple it
holds, being consistent with its indexing behavior.
---
 base/multidimensional.jl | 6 ++++++
 test/arrayops.jl         | 2 ++
 2 files changed, 8 insertions(+)

diff --git a/base/multidimensional.jl b/base/multidimensional.jl
index c9af4fef644ae..53293cd67f640 100644
--- a/base/multidimensional.jl
+++ b/base/multidimensional.jl
@@ -88,6 +88,12 @@ module IteratorsMD
 
     # indexing
     getindex(index::CartesianIndex, i::Integer) = index.I[i]
+    eltype(index::CartesianIndex) = eltype(index.I)
+
+    # iteration
+    start(index::CartesianIndex) = start(index.I)
+    next(index::CartesianIndex, state) = next(index.I, state)
+    done(index::CartesianIndex, state) = done(index.I, state)
 
     # zeros and ones
     zero(::CartesianIndex{N}) where {N} = zero(CartesianIndex{N})
diff --git a/test/arrayops.jl b/test/arrayops.jl
index 2f1b4309bc9b2..a12860f036fcd 100644
--- a/test/arrayops.jl
+++ b/test/arrayops.jl
@@ -1542,6 +1542,8 @@ end
     @test min(CartesianIndex((2,3)), CartesianIndex((5,2))) == CartesianIndex((2,2))
     @test max(CartesianIndex((2,3)), CartesianIndex((5,2))) == CartesianIndex((5,3))
 
+    @test [I1...] == [I1[n] for n in 1:length(I1)]
+
     # CartesianIndex allows construction at a particular dimensionality
     @test length(CartesianIndex{3}()) == 3
     @test length(CartesianIndex{3}(1,2)) == 3